It is desirable to know the distance traveled by a vehicle per quantity of fuel consumed during all modes of operation. In this way we can better control the operation of the vehicle to decrease the vehicle's fuel consumption. To this end a number of devices have been proposed and are in use which determine the distance traveled per given quantity of fuel consumed. Most, if not all, of these known devices are inaccurate, require regular adjustment, require special adaptation for different installations, will not determine high and low flow rates with the same degree of accuracy, and/or are unnecessarily expensive and complex.